arch/risc-v/esp32[-c3|-c6|-h2]: Add auto light sleep

[eren-terzioglu]

Summary

• Docs/risc-v/esp32[-c3|-c6|-h2]: Add autopm docs

Add autopm docs for risc-v based Espressif devices

• boards/risc-v/esp32[-c3|-c6|-h2]: Add autopm defconfig

Add autopm defconfig for risc-v based Espressif devices

• arch/risc-v/esp32[-c3|-c6|-h2]: Add auto sleep

Add auto sleep for risc-v based Espressif devices

Impact

Impact on user: Auto light sleep option added

Impact on build: No

Impact on hardware: No

Impact on documentation: autopm configuration docs added

Impact on security: No

Impact on compatibility: No

Testing

Building

Used configs:

esp32c3-devkit:autopm
esp32c6-devkitc:autopm
esp32h2-devkit:autopm

Command to build:

make -j distclean && ./tools/configure.sh esp32c6-devkitc:autopm && make -j && make download ESPTOOL_PORT=/dev/ttyUSB0 ESPTOOL_BAUD=921600 ESPTOOL_BINDIR=./

Running

Defconfig enables UART wakeup and WiFi wakeup (on supported devices) by default.

Used commands to test power consumption during WiFi operation:

ifup wlan0
wapi psk wlan0 WIFI_PASS 3
wapi essid wlan0 WIFI_SSID 1
renew wlan0

ping 8.8.8.8

For UART wakeup, sleep logs and power consumption checked

Results

System logs (Power Related debug options enabled):

...
NuttShell (NSH) NuttX-10.4.0
esp_pm_skip_light_sleep: UART wakeup still within guard window
nsh> esp_pm_skip_light_sleep: UART wakeup still within guard window
esp_pm_skip_light_sleep: UART wakeup still within guard window
nsh> esp_pm_skip_light_sleep: UART wakeup still within guard window
...

Idle system power consumption drops from 90-100 to 27-35 mA

During ping operation power consumption should drop from 90-100mA to 30-40mA

Special thanks to @tmedicci for his help